1. Field of the Invention
The present invention relates to an electric connector unit which is comprised in a tester for semiconductor elements and used for connecting a probe card to the tester, and more specifically a connector pin which is to be built in the electric connector unit.
2. Description of the Related Art
LSI chips which are formed on a wafer at a manufacturing step of the LSI chips are subjected to a function test before they are cut off into individual chips. A tester used for this function test will be described with reference to a schematic diagram shown in FIG. 1. In FIG. 1, a tester 100 is composed of a test head 101, a connecting ring 104 and a probe card 106. The test head 101 comprises a power source and a measuring instrument which are used for the test, and a test board 102 which is to be connected to the connecting ring 104 is attached to the test head 101. Probes 105 which are to be brought into contact with a pellet (an LSI chip) 108 on a wafer 107 are disposed at a center of the probe card 106 and connected to pads 110 through wires (not shown). The connecting ring 104 is a part used for electrically connecting the test board 102 to the probe card 106, and connector pins 103 which are studded on a top surface and a bottom surface of the connecting ring 104 are connected to each other in the connecting ring 104. Further, the connector pins 103 are disposed at locations which correspond to pads 109 on the test board 102 and the pads 110 on the probe card 106 respectively. Actually, the connector pins are disposed in 100 to 1000 pairs on the connecting ring 104.
FIG. 2 shows a sectional view of the connecting ring 104. In this drawing, however, only two pairs of connector pins are shown and parts which correspond to those shown in FIG. 1 are represented by the same reference numerals. In FIG. 2, connector pins 103a and 103b which are disposed in the connecting ring 104 are set in directions reverse to each other and connected by way of a connecting pipe 111. Each of the connector pins 103a and 103b is composed of a pin 112 which is kept in contact with the pad 109 of the test board 102 or the pad 110 of the probe card 106 and a casing 113 which is kept in contact with the connecting pipe 111. A main body of the connecting pipe 104 has an insulating property though the connector pins 103a, 103b and the connecting pipe 111 are made of a metal. In other words, the connecting pipes 111 for the connector pins are insulated from one another.
In each of the connector pins 103a and 103b, the pin 112 is kept in contact with the casing 113 inside the casing. Accordingly, an electric current path is formed from the pad 109 on the test board 102 to the pad 110 on the probe card 106.
The connector pin 103a or 103b described above has a structure wherein the pin 112 and the casing 113 are kept in contact with each other. Therefore, the connector pin poses a problem that portions of the pin 112 and the casing 113 which are kept in contact with each other are abraded due to friction between the metal parts, thereby causing poor contact or malfunction of the pin 112 due to metal powders.